ES2573202A1 - Acoustic panel and acoustic barrier (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Acoustic panel and acoustic barrier. The invention relates to an acoustic panel comprising: (I) an interior module (3) of mortar or concrete with plastic pellets with a baffle (4) and a support base (33) and (II) an exterior module ( 1) of perforated metal sheets inside (21) and outside (20) with recesses (34) and alternate projections (35), having surfaces that form a main inclination angle (13) with respect to a vertical plane and the recesses have surfaces forming a secondary angle of inclination (14) with respect to the vertical plane lower than the main angle of inclination; lateral metal sheets (22, 23) and upper (24) and lower (16) covers, delimiting a space filled with open cell polyurethane foam or mineral fiber wool. The invention also relates to an acoustic barrier comprising two or more acoustic panels of the invention and with methods for their manufacture. (Machine-translation by Google Translate, not legally binding)

Description

ACOUSTIC PANEL AND ACOUSTIC BARRIER

Field of the Invention The present invention relates to a new acoustic panel and acoustic barriers manufactured therefrom for protection against noise pollution caused for example by traffic in general.

Background of the invention

One of the main causes of noise pollution is road traffic. Nevertheless, is not the only one. Other possible causes are the railroad, the presence of industry, airports, ports or leisure activities. In relation to the first cause, the impressive increase in road traffic on roads entering large cities, as well as on fast roads inside them, together with urban planning problems and the lack of adequate legislation for years have produced as a consequence

15 undesirable, high rates of noise pollution. In many areas, due to the urban configuration itself, there is no other option but to screen the homes, or areas inhabited in general, through acoustic barriers. Acoustic barriers or screens represent a response to the level of noise pollution in urban areas of the periphery subject to the direct impact of traffic. In Europe there is extensive experience of more than 30 years in the construction of this type of solutions to mitigate the noise that traffic produces. Germany, France, Spain, the United Kingdom, Italy and the Benelux countries have thousands of kilometers of acoustic screens, thus responding to a social demand for noise. These acoustic barriers can be classified as absorbent and reflective. Most screens

25 acoustics installed on roads or highways are of this second type, due to economy and constructive ease. However, these screens have the disadvantage of producing multiple reflections also having a poor attenuation capacity. This observation is especially applicable in the case of tunnels, where the absence of acoustic considerations during the project can cause remarkable levels of noise reflected in a resonant cavity configuration. The reflective screens are usually formed by wood panels, corrugated sheet, cement, etc., while the screens that are called absorbents can be formed by porous concrete panels (low acoustic absorption) open cell cellular materials, cavities filled with material Acoustically absorbent fibrous or resonant cavity systems. The absorbent barriers, which can be low absorption, medium absorption and highly absorbent, are

35 those barriers capable of absorbing a significant portion of the incident acoustic energy, reducing the total level of noise in their surroundings. This reduction of noise in the environment is one of the most remarkable characteristics of the absorbent screens and what makes them desirable against the reflectors.

There are numerous scientific publications that study the issue of sound attenuation-redirection through acoustic screens from different points of view, affecting different aspects of the materials that form the barriers, their geometric configuration, phenomena of sound propagation in presence of obstacles, in the acoustic spectral characterization of the environment in noisy environments over what can be called the annoying noise threshold.

Also, different barrier or acoustic screen configurations are known in the state of the art, which are mostly reflector panels with very limited absorbent characteristics, or absorbent panels in which the subject of the reflected and diffracted components is not contemplated. , mainly due to what could be economic and technical reasons (it is well known that in general terms materials that are good reflectors have poor absorption characteristics). In view of the above, there is still a need in the prior art to provide an improved acoustic panel.

Summary of the Invention

The present invention solves the aforementioned problem by providing in a first aspect an acoustic panel comprising:

(i)

an inner module made of mortar or concrete with plastic pellets, said inner module having an upper part and a lower part, the inner module comprising a baffle on the upper part, and the lower part forming a support base; Y

(ii)

an outer module comprising: a vertical inner perforated metal sheet, an outer perforated metal sheet having alternate recesses and projections, where the projections have surfaces that form a main angle of inclination with respect to a vertical plane and the recesses have surfaces that form a secondary angle of inclination with respect to the vertical plane with the secondary angle of inclination being less than the main angle of inclination; the outer module also comprising two lateral metal sheets; a top metal closure cap; and a lower metal closing lid, delimiting said

65 metal sheets and covers an internal space comprising an open cell foam of flexible polyurethane, mineral fiber wool or a mixture of both.

The acoustic panel of the invention achieves excellent acoustic shielding by synergistically combining an inner module of composite material (mortar or concrete with plastic shot) which provides superior acoustic performance measured through the transmission loss coefficient (TL) and the acoustic absorption coefficient (α) and an external module with which it is possible to “tune” (for its reduction or

5 elimination) the most harmful and annoying part of the frequency spectrum in each case, said module being formed by perforated metal sheets with a flexible open polyurethane foam open cell foam, optionally from the recycling of mattresses or mineral fiber wool. In addition, the presence of the baffle in the upper part allows the control of the diffracted component.

In a particular embodiment of the panel the plastic pellet (also called shot in the present invention) comes from the recycling of electrical wiring sheaths. In this way the invention provides the additional advantage of revaluing a waste product, giving it an application, which prevents, that the product is removed to the environment with the risk of associated contamination, or that it has to be subjected to costly recovery processes.

In another particular embodiment the plastic pellet used in the panel is present in an amount of between 2.5% and 20% in volume with respect to the total volume of the inner module. Higher or lower percentages are possible, but in the case of higher percentages, the mechanical properties are affected. In another particular embodiment the flexible polyurethane open cell foam comes from the recycling of mattresses. In this way it is also possible to revalue a massive waste product to which it is found.

20 an application. In a particular embodiment the main angle of inclination is between 10-15 ° and the secondary angle of inclination is between 4-8 °. In this way the control of the reflected component is achieved. In a particular embodiment the deflector forms an angle equal to or less than 45 ° with respect to the vertical plane.

In a particular embodiment, the panel of the invention comprises at least one additional parallelepiped-shaped module located between the first module and the second module, the additional module comprising two main perforated metal sheets parallel to each other, two lateral metal sheets perpendicular to the main and parallel to each other, and a top metal closing lid and a lower metal closing lid perpendicular to the previous ones, and this additional module comprising the internal space delimited by the

30 sheets and covers an open cell foam made of flexible polyurethane, mineral fiber wool or a mixture of both. The presence of an additional module allows to optimize the tuning (for its reduction or elimination) of the part of the most harmful and annoying frequency spectrum in each case, since said module is formed by perforated metal sheets with an open cell foam padding of flexible polyurethane, optionally from the recycling of mattresses or mineral fiber wool.

In a particular embodiment the panel comprises two additional modules both located between the first module and the second module. In a particular embodiment the panel comprises among all the constituent modules thereof, a separation space. The separation space between two modules comprises an interposition sealant, where the sealant occupies a maximum of 20% of the space, the remaining 80% being a hollow cavity. The presence of the

The hollow cavity that in a particular embodiment has a thickness ranging from 0.1 to 0.9 millimeters, forms a resonance chamber that, in conjunction with perforated sheets, is capable of producing maximums in the absorption coefficient, at a frequency that It is a complex function of the depth of the cavity, the average diameter of the perforations, the density of perforations in the panel and its thickness. In another particular embodiment, the panel comprises a cradle space in the upper part of the module

45 interior. This element fulfills a purely decorative function, as it serves as a support for soil and a plant mass that can decorate the panel on the outside allowing greater visual and aesthetic integration in the environment. The union of two or more (generally several) panels of the invention forms acoustic barriers that constitute another aspect of the present invention.

In a particular embodiment, the barrier of the invention is also provided with one or more foundation shoes that allow it to be anchored to the ground. In another particular embodiment, the barrier of the invention further comprises one or more galvanized sheet steel joining pieces that join adjacent panels, and the panels to the foundation shoe. The different aspects and embodiments of the invention defined in the preceding paragraphs can be combined.

55 each other, as long as they are compatible. These and other advantages of the invention will be apparent in light of the detailed description thereof.

Description of the Figures

In order to help a better understanding of the features of the invention according to some

60 particular examples of practical realization thereof, and to complement this description, the following figures are attached as an integral part thereof, whose character is illustrative and not limiting: Figure 1: graph in which the measured absorption coefficient is represented for airborne noise in normal incidence as a function of frequency (Hz) for different mortar specimens loaded with percentages of polyvinyl chloride (PVC) pellet volume / total volume (v / v) of 2.5%, 5%, 10 % and 20%, where the target is

65 a mortar without pellets, and PU indicates a sample of flexible polyurethane open cell foam from mattress recycling.

Figure 2: Graph depicting the transmission loss coefficient (dB) (TL) measured for airborne noise at normal incidence as a function of the frequency for a mortar specimen loaded with a percentage of polyethylene and polyvinyl chloride shot of 20% (v / v) and for another equal test tube but with the surface porosity occluded by paraffin.

Figure 3: section of a panel according to the invention comprising an external module (1); an intermediate module

(2) and an interior module (3). Figure 4: isometric view of a panel according to the invention comprising the outer module (1); an intermediate module (2), the inner module (3) and a deflector (4). Figure 5: Detail of the lower parts of a panel of the invention, of the joining pieces (5, 7) and the joints of the joining pieces by welding (8) and / or screws (6) to the modules (1 ) and (3) and the foundation shoes (36). Figure 6: Isometric view of two particular embodiments of a connecting piece (5, 10). Figure 7: represents a particular embodiment of a panel of the invention in which the area of separation space (18) between the inner module (3) and the intermediate module (2) and the area are shown in enlarged detail

15 of separation space (19) between the outer module (1) and the intermediate one (2); and the lower (17) and upper (27) metal covers of the intermediate module (2). In addition, areas are shown in which the outer perforated metal sheet has perforations (20, 31), (dashed lines), and areas where it is not necessary for the outer perforated metal sheet (20) to have perforations (32), (continuous line) . Figure 8: side and front views of the external module (1) where the main angle of inclination (13) and the secondary angle of inclination (14) are also represented. Figure 9: side and front views of the intermediate module (2).

Detailed description of the invention

The invention is described below in reference to particular embodiments thereof and to the Figures.

25 for better understanding, without this being construed as limiting the scope of the invention. Figure 4 shows an acoustic panel according to a possible embodiment of the invention. The panel comprises an interior module 3 made of mortar or concrete with plastic pellets. The inner module 3 has an upper and a lower part. The inner module has a baffle 4 at the top and a support base 33 at the bottom. The acoustic panel further comprises an outer module 1. Fig. 8 shows an outer module 1 according to a possible embodiment of the invention. The outer module comprises a vertical inner perforated metal sheet 21, an outer perforated metal sheet 20 having alternate recesses 34 and projections 35, where the projections have surfaces that form a main angle of inclination 13 with respect to a vertical plane and the recesses have surfaces that form a secondary angle of inclination 14 with respect to the vertical plane the secondary angle of inclination being less than the main angle

35 tilt. The outer module 1 further comprises two lateral metal sheets 22, 23; a top metal closure cap 24; and a lower closing metal lid 16, said metal sheets and covers delimiting an internal space comprising an open cell foam of flexible polyurethane, mineral fiber wool or a mixture of both. The external module is called the external because it is located on the side of the sound emission source, while the internal module is called the internal because it is placed on the side that is to be protected from noise pollution. The plastic pellet that is used to manufacture the inner module can be a priori of any nature. The pellet or shot is small pieces with a general size of 1 mm or less. In a particular embodiment the plastic pellet comes from the recycling of electrical wiring sheaths.

45 Specifically, the nature of this type of plastic pellet can vary from polyethylene (PE), for example in the case of plastic from the recycling of copper cables, from cross-linked PE, for example in the case of plastic from the recycling of cables. of aluminum, or being of polyvinyl chloride (PVC) for example in the case of plastic from the recycling of both copper and aluminum cables. The average composition of the shot from the recycling of cables usually includes, in the case of polyethylene, a small amount of PVC and significant amounts of flame retardants and inorganic fillers. In the case of PVC, the content of charges such as flame retardants and carbonates reaches 40%, also presenting up to 4% polyamide. This means that materials from the recycling of electrical wiring sheaths do not easily find how to re-enter the market, due to the presence of flame retardant agents (PVC is a material that is hardly difficult to reprocess itself due to the generation of hydrochloric acid in his reprocessed

55) and in the case of cross-linked PE, in addition, due to chemical cross-linking (use of chemical products that improve mechanical properties by creating a three-dimensional network between the polymer chains and converting thermoplastic polyethylene into virtually thermosetting). The use of this type of pellet in the panels of the invention supposes an additional advantage, since it gives way to a waste product, revaluing it, and avoiding that its elimination supposes a damage for the environment. For example, plastics that come from the recycling of cables, include metals such as aluminum, in the form of aluminum hydroxide in amounts that can reach up to 70% by volume, which makes it almost impossible to reuse and additionally these residues become in a serious problem from the environmental point of view. The amount of pellet that is used with the mortar or concrete to manufacture the interior module is variable. In

In a particular embodiment, the plastic pellet is present in the module in an amount between 1% and 40% by volume with respect to the total volume of the module. Higher amounts are possible, but in exchange the resulting mechanical properties of the panel are compromised. In another particular embodiment the amount of plastic pellet is between 3% and 30%. In another particular embodiment, between 5% and 25%, and in another embodiment between 8% and 18%. Examples of particular embodiments are among other amounts of 2.5%, 5%, 10%, 15%, and 20%.

5 The presence of the plastic shot and the additional porosity it provides to the resulting mortar or concrete material results in an excellent combination of acoustic characteristics measured through the acoustic absorption coefficient (α) and the transmission loss coefficient (TL ). Thus it is especially remarkable and interesting in these materials, for example in the case of PVC pellets that samples containing 2.5%, 5%, 10% or 20% (v / v) of PVC pellets have an intense absorption peak located at low frequencies as shown in Figure 1. Precisely the areas of low and medium frequencies (in airborne noise), corresponding to the high and medium wavelengths are characteristically difficult to attenuate or deflect by reflection having an important ability to overcome obstacles (due to the relationship between the wavelength and the size of the obstacle that conditions these phenomena). Fig. 2 illustrates the transmission loss coefficient (TL) measured for airborne noise at normal incidence as a function of the frequency for a

15 mortar specimen loaded with a 20% (v / v) shot percentage of PE and PVC. It can be seen that the mortar loaded with shot blast has an average transmission loss value of about 50dB (between 600 Hz and 6500 Hz) presenting very important peaks related to the percentage of plastic content, internal porosity and porosity open to the surface. To show the important weight in the response of these materials the porosity open to the surface of the mortar loaded with shot, also presented in Figure 2, the values of the coefficient of losses per transmission for the same specimen but with the surface porosity occluded by paraffin. The results shown in Figures 1 and 2 were both measured in normal incidence on cylindrical specimens 30 mm long in a Brüel & Kjaer impedance tube. The external module 1 of the acoustic panel according to a possible embodiment of the invention comprises a sheet

25 vertical inner perforated metal 21, and an outer perforated metal sheet 20. The external module further comprises two lateral metal sheets 22, 23 which may or may not be perforated, in accordance with particular embodiments of the external module. The upper metal closing lid 24 and the lower metallic closing lid 16 are not perforated. In another particular embodiment the outer perforated metal sheet 20 has areas that do not have perforations. Fig. 8 shows the particular embodiment where the outer perforated sheet 20 is drawn with a dotted line where the surfaces have perforations 31 and with a continuous line where the surfaces are without perforations 32. The metal sheets are commercially available and are preferably manufactured Galvanized steel Perforated sheets may have perforations that have one or several different diameters. Their thicknesses are generally between 0.75 mm and 2 mm. Generally the diameters of the perforations are between 0.5 mm and 5

35 mm, while the separation between perforations is usually a multiple between 1.5 and 3 times the diameter of the perforations (in the case of single diameter). The external module 1 comprises inside an open cell polyurethane foam that can be a priori of any type and origin. In a preferred embodiment these modules may comprise flexible polyurethane open cell foam and more particularly flexible polyurethane open cell foam that comes from mattress recycling. In another preferred embodiment, mineral fiber wool (porous material that may or may not come from the recycling of construction materials) is used for its manufacture. Mineral fiber wool is used for example when there are conditions in relation to fire resistance. The flexible polyurethane open cell foam of mattress recycling also has the additional advantage that it provides an outlet for a waste product and allows it to be revalued. In another particular embodiment,

45 uses a mixture of open cell foam of flexible polyurethane and mineral fiber wool in any relative proportion. Both types of materials are generally used as small fragments of the order of the millimeter. In the case of flexible polyurethane open cell foam that comes from mattress recycling, this material is generally used in fragments that have an average size of 1 mm. The panel of the invention comprises a single external module 1 that is oriented towards the sound source. Being filled with pieces of open-cell polyurethane foam (or mineral wool), optionally from recycling, the relationship between the surface of the solid-gas interface and the volume of the inner air content increases greatly increasing the extent of the boundary layer, which is the submicrometer layer in which the Reynolds number decreases to very small values and the viscous and thermal exchange effects predominate resulting in strong attenuations of the acoustic field. Also the presence of foam

55 open cell increases a parameter known as tortuosity that is related to the difference between the minimum geometric distance between two points and the one that actually travels the wavefront when it propagates through a labyrinthine structure. The typology of the external module 1 therefore corresponds to a non-classical Helmholtz resonator, modified, filled with absorbent and tunable material with multiple cavity made of perforated sheets. The inner module 3 is provided with a deflector 4 at the top as shown in Fig. 4. According to a possible embodiment of the invention the deflector is inclined at an angle 15 as shown in Figure 7, the same or less than 45º with respect to the vertical plane. In another particular embodiment, the deflector 4 forms an angle equal to or less than 40 °, more particularly equal to or less than 35 °. Non-limiting illustrative examples of the angle are 44, 43, 42, 41, 39, 38, 37, 36, 34, 33, 32, 31, 30. Baffle 4 serves to

65 control the diffracted component as desired in each particular case. The panel optionally comprises as described below an intermediate module that appears to be represented in Fig. 3, 4, 5 and 7.

According to an embodiment of the invention, the panel of the invention comprises a cradle-shaped space 9 in the upper part of the inner module 3 as shown in Fig. 3. Its function is to serve as a possible support (ground ) for a plant mass that can do decorative functions to cover the outer face and allow greater visual and aesthetic integration in the environment.

In accordance with an embodiment of the invention, and as can be seen in both Figures 3, 4, 7 and 8, the panel of the invention comprises an external module 1 having a particular configuration. In this sense, the outer perforated metal sheet 20 of the outer module has alternate recesses 34 and projections 35, where the projections have surfaces that form a main angle of inclination 13 with respect to the vertical plane and the recesses have surfaces that form a secondary angle of inclination 14 with respect to the vertical, the secondary angle of inclination being less than the main angle of inclination. In a more particular embodiment, the main angle of inclination 13 is between 10-15 °, and may take values of 10 °, 11 °, 12 °, 13 °, 14 ° or 15 °. In another more particular embodiment, the secondary angle of inclination 14 is between 4-8 °, and can take values of 4, 5, 6, 7 and 8. This configuration allows redirecting the reflected component, generating interference, and by its geometry acts as a diffuser, reflecting the sound

15 direct and distributing its power in different directions. The geometry of the outer perforated metal sheet 20 of the panel of the invention is conditioned by compliance with the requirements of acoustic reflection (acoustic reflection law in the frequency range to be attenuated according to UNE EN 1793-3: 1998: Reducing devices of road traffic noise Test method for determining acoustic behavior Part 3: Standardized spectrum of traffic noise). According to this law, if the height of the obstacle is at least two to four times the wavelength of the incident sound wave, the angle of reflection of the incident wavefront (with respect to the normal defined by the surface of the obstacle ) with which the sound wave bounces at greater amplitude is the same as that of incidence. If an obstacle is small in relation to the wavelength of the incident wave, it may surround it, and if the obstacle is "large" in relation to the incident wavelength, the wave will bounce off it.

The panel of the invention according to a particular embodiment is formed by an external module 1 and an internal module 3; It has excellent acoustic characteristics due to the synergistic combination of the attenuation spectrum of both modules. The internal concrete or mortar module 3 with added plastic shot, has an excellent combination of mass, transmission loss coefficient and absorption coefficient, and its effect is complemented by the additional use of at least one tunable external module 1 composed of perforated metal sheets and a flexible polyurethane cell foam padding, optionally recycled, (or mineral fiber wool if there are requirements in relation to fire resistance). Figure 1 presents the acoustic absorption coefficient as described above. As can be seen in Figure 1, the absorption coefficient of mortars with pellets has a pair of intense absorption peaks. By superimposing the response of the plastic filled mortar and the PU one, an amazing result is obtained

35 absorption coefficient in a wide spectrum. Figure 3 shows an acoustic panel according to a particular embodiment of the invention which also comprises an external module 1 and an internal module 3, an additional module 2 located between 3 and 1. Fig. 9 shows a particular embodiment of the additional module 2. The additional module 2 comprises two main perforated metal sheets parallel to each other 25, 26. It also comprises two lateral metal sheets 29, 30 perpendicular to 25, 26 and parallel to each other, which according to a particular embodiment are perforated and according to Another particular embodiment are not perforated. The module 2 comprises an upper metal closing lid 27, and a lower metallic closing lid 17 both unperforated. The additional module 2 is also tunable just like the outer module and contributes, like this one, to the elimination, partial or total, of the most harmful and annoying part of the frequency spectrum

The internal space of the additional module 2 comprises inside an open-cell polyurethane foam that can be a priori of any type and origin. In a preferred embodiment this module may comprise flexible polyurethane open cell foam and more particularly flexible polyurethane open cell foam that comes from mattress recycling. In another preferred embodiment, mineral fiber wool (porous material) is used for the manufacture of the additional module 2 as described above for the outer module 1. The mineral fiber wool is used for example when there are conditions in relation to the resistance to fire. The flexible polyurethane open cell foam of mattress recycling also has the additional advantage that it exits a waste product and allows it to be revalued. In another particular embodiment, a mixture of open cell foam of flexible polyurethane and mineral fiber wool in any relative proportion is used. Both types of materials are generally used as small

55 fragments (of the order of the millimeter). In the case of the flexible polyurethane open cell foam that comes from the recycling of mattresses, this material is generally used in fragments whose average size is desirable to be 1 mm. In a particular embodiment the panel of the invention comprises two additional modules 2 both located between the inner module 3 and the outer module 1. Said modules may be the same or different from each other. By adding the response of one or two additional modules 2, the panel response can be reinforced in frequency zones that are to be eliminated, achieving even greater acoustic response in terms of attenuation. In order to manufacture modules 2 and 1, commercial metal sheets are preferably made of perforated or unperforated galvanized steel, as described above. The sheets are cut by laser or water jet to later be spot welded (by welding "Tungsten Inert Gas"

65 (TIG)) with the help of a tool that guarantees the required geometry. In a more particular embodiment, 2 mm thick welded galvanized sheet steel with perforations is used for the outer module 1

3 millimeters in diameter and 7 millimeters apart between them forming a repetitive translational pattern in two dimensions. These panels are laser cut and subsequently welded (by TIG welding) with the help of a tool that guarantees the required geometry, for example: a main angle of inclination 13 of 10º and secondary angles of inclination 14 of 4º to generate interference. The bottom cover 16 and 17 of each 5 of the perforated modules 1 and 2 are welded (TIG spot welding) after incorporating the filling (polyurethane or fiber wool), introducing a final cover welding, rock wool layer that acts as a heat deflector. For the intermediate module, for example, welded galvanized steel sheet with perforations of 2 millimeters in diameter and 3 millimeters apart (rows and columns) is used, corresponding to a separation of 5 millimeters between centers forming a repetitive pattern. These

10 sheets are also laser cut and subsequently welded (by TIG welding) with the help of a tool that guarantees the required geometry. The manufacture of the interior module 3 can be done either in one piece, or in parts that are subsequently joined to the work site by developing the module 3 in situ by means of traditional formwork means. In a particular embodiment the inner module 3 is manufactured conventionally in a piece with concrete and 15%

15 (v / v) PVC wire shot recycling, having a baffle forming an angle 15 of 36º. According to a particular embodiment of the panel of the invention, the panel comprises among all the constituent modules thereof a separation space. Fig. 7 shows in enlarged detail a particular embodiment of the panel of the invention in which the separation space 18 located between the inner module 3 and the intermediate module 2 and the separation space 19 located between the outer module 1 and the module

Intermediate 2. The separation space comprises a sealant, which occupies a maximum of 20% of said separation space, the remaining 80% being a hollow cavity. The sealant can be located in principle in any part of said space, for example in the center, on the sides, around a frame formed, etc. This hollow cavity can have a variable thickness that generally ranges from 0.1 to 0.9 mm,

25 particularly between 0.2 and 0.7 mm, for example 0.3, 0.4, 0.5 or 0.6 mm. The sealant used is a conventional interposition sealant of the flexible silicone or polyurethane type that also functions as an adhesive. These hollow cavities between modules act as resonators. The presence of the cavities that in a particular embodiment has a thickness ranging from 0.1 to 0.9 millimeters, form a resonance chamber that, in conjunction with the perforated sheet is capable of producing maximums in the absorption coefficient, at a

30 frequency which is a complex function of the depth of the cavity, the diameter, the density of perforations in the panel and its thickness. According to a particular embodiment of the invention the resonance frequencies corresponding to panels 1 and 2 are below 1 kHz, while the two frequencies corresponding to the cavities of 0.2 and 0.5 mm are in the zone between 2 and 3.5 kHz. These frequencies and the acoustic spectrum are checked

35 experimentally by the usual means of measurement in situ. Fig. 3 shows in addition to an acoustic panel according to an embodiment of the invention, a profile view of an acoustic barrier according to a particular embodiment of the invention. The acoustic barrier of the invention comprises two or more adjacent panels of the invention. In the particular embodiment of the barrier of the invention illustrated in Fig. 3 the barrier is provided with at least one foundation shoe 36. The presence of

40 seat shoes (a small foundation) is necessary for placement in the case of undeveloped land. Fig. 3 further shows junction pieces 5, 7, 10 of galvanized sheet steel of the various elements according to a particular embodiment. The joining pieces join modules, adjacent panels, and panels to the foundation shoe, the joints being screws 6 or spot welding 8.

45 In order to ensure the mechanical connection between the external modules and the concrete (or the seat shoes), steel pieces of different thicknesses folded in a folding machine are used, as shown according to a particular embodiment thereof in Figure 6 that are screwed to the concrete. (with the help of expandable threaded bushings) and welded by points to the perforated barriers. The connecting pieces 10 join modules at the top of the panels, with screws and welding. Parts 5 join internal modules 3 to concrete

50 by screws. The study of the location of the barrier (distance to the sound source, height above the level of sound emission and distance to the area where maximum attenuation is necessary) of the barrier, is very important and an essential part of the previous initial process It will depend on each particular case. There are several well-known analytical models for an expert that can be used for the specific design of a barrier in each case.

55 The geometry and configuration of the external module 1 (perforation density and diameter thereof), as well as the total height of the panel, the content in percentage by volume of plastic, the angle and the ratio of heights between the baffles and The panel is variable depending on the spectrum to be attenuated. This spectrum must be previously measured at each location by taking a number of samples that are statistically significant.

The panel and the barrier of the invention represent a substantial improvement with respect to the panels and the current commercial acoustic barriers by synergistically combining different elements and aspects as described above. The invention is not limited to the specific embodiments described above but also covers, for example, the variants that can be made by the average person skilled in the art within

65 which follows from the claims.

Claims (11)

1. Acoustic panel comprising: (i) an interior module (3) made of mortar or concrete with plastic pellets, having 5 said inner module an upper part and a lower part, the inner module comprising a deflector (4) in the upper part, and the lower part forming a support base (33) and (ii) an outer module (1) comprising a vertical inner perforated metal sheet (21), an outer perforated metal sheet (20) having alternate recesses (34) and projections (35) 10, where the projections have surfaces that form a main angle of inclination (13) with respect to a vertical plane and the recesses have surfaces that form a secondary angle of inclination (14) with respect to the vertical plane, the secondary angle of inclination being less than the main angle of inclination; the outer module (1) further comprising two lateral metal sheets (22, 23); a top metal closure cap (24); Y 15 a lower metal closing lid (16), said metal sheets and covers delimiting an internal space comprising an open cell foam of flexible polyurethane, mineral fiber wool or a mixture of both. 2. Panel according to claim 1 wherein the plastic pellet comes from the recycling of electrical wiring sheaths. 3. Panel according to claim 1 or 2, wherein the plastic pellet is present in an amount between 2.5% and 20% by volume with respect to the total volume of the inner module (3). 4. Panel according to one of claims 1 to 3, wherein the flexible polyurethane open cell foam comes from mattress recycling. 5. Panel according to one of claims 1 to 4, wherein a main angle of inclination (13) 25 is between 10-15 ° and the secondary angle of inclination (14) is between 4-8 °.

6.

Panel according to one of claims 1 to 5, wherein the deflector (4) forms an angle (15) equal to or less than 45 ° with respect to the vertical plane.

7.

Panel according to any one of the preceding claims comprising at least one additional module (2) located between the inner module (3) and the outer module (1), the

30 additional module (2) two main perforated metal sheets parallel to each other (25, 26), two side metal sheets (29,30) perpendicular to (25,26) and parallel to each other, a top metal closing lid (27) , and a lower metal closing lid (17) perpendicular to (29,30,25,26) and this additional module comprising in the internal space delimited by the sheets and covers an open cell foam of flexible polyurethane, fiber wool mineral or a mixture of both. Panel according to the preceding claim comprising two additional modules (2) both located between the inner module (3) and the outer module (1). 9. Panel according to any one of the preceding claims comprising among all the constituent modules thereof, a separation space comprising an interposition sealant, where the sealant occupies at most 20% of the space, the remaining 80 % a 40 hollow cavity.

10.

Panel according to the preceding claim wherein the hollow cavity has a thickness ranging between 0.1 and 0.9 millimeters.

eleven.

Panel according to any one of the preceding claims comprising a cradle-shaped space (9) in the upper part of the inner module (3).

12. Acoustic barrier comprising two or more panels according to any one of the preceding claims.

13.

Barrier according to claim 12 provided in addition to one or more foundation shoes (36).

14.

Acoustic barrier according to claim 12 or 13, further comprising one or more connecting pieces (5,

7, 10) of galvanized steel sheet joining adjacent panels, and the panels to the 50 foundation shoe (36).